1) How long have you been on T?
About four and a half years.
2) What changes have you seen (positive and negative [if any])?
Too many to count...but I'm not thrilled that my upper back is getting hairy, I wish I had more body hair elsewhere, my hairline has receded quite a bit (I'm making my peace with that), I still hope to eventually sound like James Earl Jones (I'm mostly joking, but my last vocal shift, a fairly small one, was a couple of months ago, so I am waiting for the voice changes to finally end), and I wish I could be a little more patient and less irritated with people who drive badly on the freeway or act inconsiderately in the grocery store (but patience takes time and effort, and I am still in adolescence, for all intents and purposes).
3) In a relationship with a lesbian, how has it affected the relationship?
Sorry, I don't do women.
4) Anyone on here that is the girl in the relationship with the FTM? (if so, what has been your experience [were you worried about the changes, do you like the changes, etc.?]
Not I, but I think you will find a couple of SOs if you spend some time on the site.
5) After what amount of time on T can you begin to work out and have the results of muscle mass?
Talk to your doctor, but I kept exercising with no problems. I'm not sure when I noticed gains in muscle mass because I was more focused on other effects.